The present invention pertains generally to strengthening solid propellants for rocket motors and recoilless guns and in particular to improving the structural integrity of reinforced high-thrust rocket motors and other recoilless systems.
The high thrust, high mass flow, and short burning times of high-acceleration recoilless gun systems and rocket motors, such as those used in tube-launched weapon systems, place the propellant under severe shock or stress conditions which can destroy the physical integrity of the gun or rocket motor. Resulting from the cracks and the break-up of the propellant is an uncontrolled increase in the burning-surface area and thus the supply of gas. These problems plus the total impulse requirements from a system of highly constrained dimensions and weight mitigate against the use of double-base propellants in high-thrust rockets, such as tube-launched rockets, even though double-base propellants are less smokey, corrosive, expensive, and toxic than the presently used case-bonded composite propellants. The problems of smoke and toxicity are especially serious for tube-launched rockets and recoilless guns because of the close proximity of people to their use. An additional problem with presently used composite propellants is the excessive noise during combustion of the high thrust, very short-burning rockets.
Previous attempts at strengthening a double-base propellant with a reinforcing substrate involved bonding one or two thin sheets of propellant to a flexible metallic or non-metallic sheet or screen by pressure, adhesive, or curing the propellant around the substrate. All of these attempts had the problem of not producing a sufficiently strong and complete bond between the substrate and propellant as well as problems arising from the choice of substrate. Since the propellant was not securely bonded, combustion flashed into the unbonded propellant areas and caused catastrophic failure of the rocket motor and recoilless guns. Further, adhesives, when used, interfered with the propellant's combustion. The effectiveness of these previous attempts to utilize smokeless propellants was so poor that the very objectionable case-bonded composite propellants continued to be used.